Method for improving access performance on track with re-allocation sector in a hard disk drive

ABSTRACT

A hard disk drive replaces a defective sector with a spare sector. When accessing a track having the defective sector, all normal sectors except for the defective sector are formerly accessed and then, a re-allocation sector which has replaced the defective sector is later accessed. In this manner, the number of searches is reduced during reading/writing (accessing) a track having defectives, thereby improving a data transmission of a hard disk drive.

CLAIM FOR PRIORITY

This application makes reference to, incorporates the same herein, andclaims all benefits accruing under 35 U.S.C. §119 from an applicationfor METHOD FOR IMPROVING ACCESS PERFORMANCE ON TRACK WITH RE-ALLOCATIONSECTOR earlier filed in the Korean Industrial Property Office on Dec.31, 1996, and there duly assigned Ser. No. 82656/1996, a copy of whichapplication is annexed hereto.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a mass storage device such as a harddisk drive, and more particularly to a method for improving a read/writeperformance on a track having a re-allocation sector in a hard diskdrive.

2. Related Art

Hard disk drive (HDD) is widely used as an auxiliary memory device of acomputer system because it can access a large amount of data at highspeed. Typically, the hard disk drives (HDD) include one or moremagnetic disks defining a multiplicity of concentric data tracks. Eachdata track is divided into alternating data and servo sectors withintersector gaps therebetween. The data sector are used for the storageof main data or user information. The servo sectors are used for thestorage of control data such as automatic gain control data, trackaddresses and tracking servo patterns for use in positioning a head.Magnetic disk drives having high data density generally rely upon servocontrol systems for moving a selected transducer (head) from a departuretrack to a destination track location when data information is writtenor read from the disk.

A typical data sector includes a plurality of identification (ID)regions, data regions and PAD (postamble data) regions serving asintersector gaps therebetween. The servo sector includes a preamble, aservo address mark SAM, a gray code, bursts A, B, C, and D, and a PAD.The preamble, a so-called servo synchronization, provides a clocksynchronization during reading the servo information and provides a gapin front of the servo sector to indicate the servo sector. The servoaddress mark SAM indicates a beginning of the servo sector to provide asynchronization for reading the following gray code. That is, the servoaddress mark SAM provides a reference point for generating varioustiming pulses regarding the servo control. The gray code provides trackinformation, i.e., the track number. The bursts A, B, C and D provide aposition error signal PES required for the track seek and the trackfollowing. The PAD provides a transition margin as a data sector in theservo sector.

When there is a defective sector, the hard disk drive re-allocates aspare sector prepared in the disk for the defect sector. Thereafter,upon receipt of an access command for accessing the defective sectors ina defective track, the hard disk drive searches a defective list in amaintenance area of the disk to check whether the track has a defectivesector. If the track has a defective sector, the hard disk drive willaccess up to a sector preceding the defective and search there-allocation sector that has replaced the defective sector, to accessthe re-allocation sector. Thereafter, the hard disk drive moves to theoriginal track to access the next sectors. Various techniques forallocation replacement of defective sectors in a hard disk drive can befound, for example, in U.S. Pat. No. 4,405,952 for Apparatus ForDetecting Faulty Sectors And For Allocating Replacement Sectors In AMagnetic Disc Memory issued to Slakmon, U.S. Pat. No. 4,631,723 for MassStorage Disk Drive defectiveive Media Handling issued to Rathbun et al.,U.S. Pat. No. 4,706,136 for Method For Controlling A Magnetic DiskMemory issued to Wentzel et al., U.S. Pat. No. 4,746,998 for Method ForMapping Around defectiveive Sectors In A Disc Drive issued to Robinsonet al., U.S. Pat. No. 4,914,530 for Media defective Management WithinDisk Drive Sector Format issued to Graham et al., U.S. Pat. No.5,075,804 for Management Of defective Areas In Recording Media issued toDeyring, U.S. Pat. No. 5,235,585 for Reassigning defectiveive Sectors OnA Disk issued to Bish et al., U.S. Pat. No. 5,271,018 for Method AndApparatus For Media defective Management And Media Addressing issued toChan, and U.S. Pat. No. 5,285,436 for Method Of Avoiding Mediumdefectives In Record/Reproduce Apparatus issued to Moribe.

Generally, the contemporary hard disk drive must search for defectivesectors every time in order to access the re-allocation sectorscorresponding to the defective sectors, so that a data transmission of ahost computer may be lowered, which results into a deterioration of thedrive performance.

SUMMARY OF THE INVENTION

Accordingly, it is therefore an object of the present invention toprovide an improved hard disk drive and process for writing and readinginformation data on a magnetic disk.

It is also an object to provide a hard disk drive and process withimproved defective management to improve a data transmission rate.

It is further an object to provide a method for reducing the number ofsearches during a read and write operation (accessing) of a track havingdefective sectors to improve a data transmission of a hard disk drive.

It is another object to provide a memory hard disk and process ofproviding improved drive performance when accessing a track havingdefective sectors to improve drive performance.

It is yet another object to provide a hard disk and a process ofimproving an access performance in a hard disk drive by accessing allnormal sectors except for the defective sector and then, accessing are-allocation sector which has replaced the defective sector, whenaccessing a track having the defective sector.

These and other objects of the present invention can be achieved by amethod for improving data access operation of a hard disk drive by thesteps of determining whether a track of a magnetic disk contains adefective sector; when the track of the magnetic disk contains thedefective sector, re-allocating the defective sector with are-allocation sector from a re-allocation area of the magnetic disk; andwhen the track containing the defective sector is being accessed duringone of a read and a write operation, accessing all normal sectors of thetrack except for the defective sector, and then, accessing there-allocation sector which has replaced the defective sector to improvedata transmission of the hard disk drive.

The present invention is more specifically described in the followingparagraphs by reference to the drawings attached only by way of example.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the present invention, and many of theattendant advantages thereof, will become readily apparent as the samebecomes better understood by reference to the following detaileddescription when considered in conjunction with the accompanyingdrawings in which like reference symbols indicate the same or similarcomponents, wherein:

FIG. 1 illustrates a common hard disk drive assembly;

FIG. 2 is a partial cross-sectional diagram of multiple disks in a harddisk drive;

FIG. 3 illustrates a data format of respective tracks on disk surfaces;

FIG. 4 illustrates a servo information pattern written on the servosector of FIG. 3;

FIG. 5 is a system block diagram of a common hard disk drive withmultiple disks;

FIGS. 6A and 6B are diagrams for explaining that a defective sector isreplaced by a re-allocation sector;

FIG. 7 is a diagram for showing a buffer RAM including buffer pointersaccording to an embodiment of the present invention; and

FIG. 8 is a flow chart of a process of accessing a track havingdefectives according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings and particularly to FIGS. 1 and 2, whichillustrates a common hard disk drive assembly supporting multiple disks.As shown in FIG. 1, the hard disk drive is constructed with a generally,rectangularly shaped base serving as a frame providing a major interiorsurface accommodating a plurality of information storage disks 2coaxially mounted in a stack upon a spindle hub assembly 5 driven by amotor (not shown) mounted on base to provide a plurality of cylindricalbase surfaces that serve as a memory into which binary information datamay be written and read, an actuator 6 mounted upon base, a voice coilmotor 10 positioned to respond to electrical control signals and therebyarcuately displace a proximal end of actuator 4, and a multi-leadflexible ribbon cable electrically coupling arm with the correspondingterminal pins of terminal. Actuator arm supports, at its distal end, aplurality of electromagnetic transducers commonly known as read/writeactuator heads 4 corresponding to the distinct separate cylindrical basesurfaces of disks 2 that serves as memories. In the embodiment of thedisk drive chosen for the purpose of illustration, two informationstorage disks are utilized. The information storage disks 2 include afirst storage disk with top and bottom surfaces 2A and 2B and a secondstorage disk with top and bottom surfaces 2C and 2B as shown in FIG. 2.The spindle motor assembly 14 includes a non-rotating spindle shaft (notshown) that is securely fastened to the base.

A disk 2 on which information data transferred from a host computer ismagnetically written, revolves at a constant speed. The transducer head4 mounted on a distal end of the actuator 6 floats, at a particularinterval, on a surface of the disk 2 which revolves at a constant speed,so as to read and write information data. An iron piece 12 is attachedto another end of the actuator 6. The actuator 6 is supported by a pivotbearing 8 and includes a coil 10 of a voice coil motor which is mountedbetween the pivot bearing 8 and the iron piece 12. The actuator 6revolves on an axis of the pivot bearing 8 by the voice coil motor, toradially move with respect to the disk 2. An outer crash stop 14 ismounted on base to prevent the head 4 from getting out of the disk 2. Amagnet 16 (sometimes, called a inner crash stop) contacts with the ironpiece 12 attached on another end of the actuator 6 by a magnetic forcein case of nonuse of the hard disk drive, so as to fix the actuator 6.

FIG. 2 illustrates a partial cross-sectional diagram of the disks in ahard disk drive adopting a multi-platter technique. The multi-platter isadopted for maximizing a data storage capacity. As shown in FIG. 2, twosheets of the disks 2 are mounted on a driving axle of a spindle motor14. Four heads 4A to 4D attached on arms extending horizontally from theactuator 6 are placed on surfaces 2A to 2D of the disks 2, respectively.Each of the disk surfaces 2A to 2D has a plurality of tracks formedthereon along concentric circles, and the respective tracks have tracknumbers TRACK₋₋ 0-TRACK₋₋ N assigned thereto. The tracks of therespective disk surfaces 2A to 2D having the same track numbers arecommonly called a cylinder. Therefore, the same track numbers of therespective disk surfaces are defined by the cylinder numbers. Forexample, a cylinder number CYLINDER₋₋ 0 is assigned to all the trackshaving the same track number TRACK₋₋ 0 of the respective disk surfaces2A to 2D.

The hard disk drive selectively places the heads on any one of thetracks on the disks by a servo mechanism. Placing a head on a particulartrack is achieved by two steps of servo control modes such as a trackseek and a track following. The track seek is a step for moving the headfrom a current track to a target track and is called a seek mode. Thetrack following is a step for accurately following a sought track and iscalled a following mode. Once the head is placed on a track, the headshould continue to follow a center line of the track in order to performan accurate read/write operation. For the track seek, the trackfollowing, and the data write operations, tracks on the disk surfaceshave a data format as shown in FIG. 3, in which servo sectors and datasectors are alternately arranged. Further, FIG. 4 illustrates a servopattern written in the servo sector of FIG. 3.

Referring to FIG. 3, the respective tracks corresponding to the headsHEAD₋₋ 0-HEAD₋₋ 3 have the servo sectors and the data sectors writtenthereon alternately. The servo sectors are prepared for a servo controlsuch as the track seek and track following, and the data sectors areprepared for recording user data thereon.

FIG. 3 illustrates, by way of example, a sector format for four tracksformed on the same cylinder of the disks corresponding to the respectiveheads in a hard disk drive including two sheet of the disks. As shown inFIG. 3, the data sector commonly includes an ID (identification) fieldon which header information for discriminating data sector is written,and a data field on which digital data is written. The servo sectors areplaced in front and rear of the data sector.

FIG. 4 illustrates servo information written on the servo sector. Theservo sector includes a preamble, a servo address mark SAM, a gray code,bursts A, B, C, and D, and a PAD. The preamble, a so-called servosynchronization, provides a clock synchronization during reading theservo information and provides a gap in front of the servo sector toindicate the servo sector. The servo address mark SAM indicates abeginning of the servo sector to provide a synchronization for readingthe following gray code. That is, the servo address mark SAM provides areference point: for generating various timing pulses regarding theservo control. The gray code provides track information, i.e., the tracknumber. The bursts A, B, C and D provide a position error signal PESrequired for the track seek and the track following. The PAD provides atransition margin as a data sector in the servo sector.

Turning now to FIG. 5, which illustrates a high density hard disk driveHDD constructed according to the principles of the present invention.The HDD includes, for example, two magnetic disks 110 and correspondingfour transducer heads 112, a transducer head assembly 114 in an E-shapehaving actuator arms each for supporting a respective pair of transducerheads 112, a preamplifier 116, a read/write channel circuit 118, a diskdata controller (DDC) 120, a buffer random-access-memory (RAM) 122, amicro-controller 124, a memory 126, a VCM (voice coil motor) driver 128,a voice coil motor 130, a spindle motor driver 132, a spindle motor 134for rotating the magnetic, head 112 across the surface of the disk 110.

Preamplifier 116 is electrically connected to the transducer headassembly 114 for amplifying a predetermined signal read out from thedisk 110 using the transducer head 112 and transmitting the amplifiedsignal to the read/write channel circuit 118. For the purpose of writingdata onto the disk 110, the preamplifier 116 applies encoded writingdata transmitted from the read/write channel circuit 118 to a designatedtransducer head from the magnetic heads 112 to be recorded on the disk110. At this time, the preamplifier 116 selects one of the magneticheads 112 according to a control signal generated from a disk datacontroller (DDC) 120 under the instruction of a micro-controller 124.

Read/write channel circuit 118 is connected between the preamplifier 116and the DDC 120 for decoding data pulses from an input signal receivedfrom the preamplifier 116 to generate read-out data, and for decodingwriting data received from the DDC 120 to transmit the decoded data tothe preamplifier 116. The read/write channel circuit 118 generates aposition error signal (PES) by decoding head position information, i.e.,a part of servo information, which is recorded on the disk, andtransmits the same to the micro-controller 124.

The DDC 120 is controlled by the micro-controller 124 to record the datareceived from a host computer via the read/write channel circuit 118 andthe preamplifier 116 or to transmit the data read out from the disk 110to the host computer. The buffer RAM 122 temporarily stores data beingtransferred among the host computer, the micro-controller 124, and theread/write channel circuit 118. The micro-controller 124 controls thetrack seek and the track following in response to a read or writecommand received from the host computer. The memory 126 stores anexecution program of the micro-controller 124 and various settingvalues. The VCM driver 128 generates a driving current for driving theactuator 130 in response to a head position control signal generatedfrom the micro-controller 124. The driving current generated from theVCM driver 128 is applied to the actuator 130. The actuator 130 movesthe heads 112 on the disks 110 according to a direction and level of thedriving current received from the VCM driver 128. A spindle motor driver132 drives the spindle motor 134 according to a disk revolution controlsignal generated from the micro-controller 124.

Generally, when there is a defective sector generated under a userenvironment, the contemporary hard disk drive re-allocates a sparesector prepared in the disk for the defective sector. Thereafter, uponreceipt of an access command for accessing the defective sectors in adefective track, the hard disk drive searches a defective list in amaintenance area of the disk to check whether the track has a defectivesector or not. If the track has a defective sector, the hard disk drivewill access up to a sector preceding the defective and search there-allocation sector that has replaced the defective sector, to accessthe re-allocation sector. Thereafter, the hard disk drive moves to theoriginal track to access the next sectors. Consequently, thecontemporary hard disk drive must search the defective sectors everytime in order to access the re-allocation sectors corresponding to thedefective sectors, that a data transmission throughput to the hostcomputer may be lowered, which results into a deterioration of the driveperformance.

If the hard disk drive has a defective sector under the userenvironment, the defective sector will be replaced by a spare sectorprepared in the disk. With reference to FIG. 6, if a sector 2 has adefect as shown in FIG. 6A, the hard disk drive will re-allocate thedefective sector 2 with a spare sector in the re-allocation area shownin FIG. 6B. The hard disk drive according to the present inventionestablishes buffer pointers as shown in FIG. 7, in order to reduce thenumber of searching operations, in case of the defective sector, therebyto improve the data transmission throughput of the disk drive.

Referring to FIG. 7, there is illustrated a diagram for showing a statusof buffer pointers in the buffer RAM 122 when starting a data accesssequence in the track having the sector as shown in FIGS. 6A and 6B. Asshown in FIG. 7, a primary buffer pointer and a secondary buffer pointerare set so as to access all the sectors except for the defective sectorin the track. Upon beginning of the data access sequence, the primarybuffer pointer is set so as to point a buffer area BF0 corresponding toa first sector out of the object sectors, and the secondary bufferpointer is set so as to point a buffer area BF3 corresponding to asector which is placed just after the defective sector 2. Further, astart address and an end address of the primary buffer pointer are set.

Now, the operation of reading data from a sector in a track andtransferring the data to the host computer will be described in detailwith reference to FIGS. 5 through 8.

At step 200, the micro-controller 124 interfaces with the disk datacontroller 120, to set a primary buffer pointer, and the start addressand the end address of the primary buffer pointer in the buffer RAM 122.With reference to FIGS. 6 and 7, the start address of the primary bufferpointer is set to the buffer area BF0 in which data of the sector 0 isto be stored, and the end address is set to the buffer area BF1 in whichdata of the sector 1 is to be stored. Thereafter, at step 202, themicro-controller 124 interfaces with the disk data controller 120 to seta secondary buffer pointer, and set the start address of the secondarybuffer pointer to a buffer area of a sector which is placed just afterthe defective sector. That is, the start address of the secondary bufferpointer is set to the buffer area BF3 in which data of the sector 3 isto be stored.

Then, at step 204, the micro-controller 124 reads data from the sectors0 and 1 according to the addresses that the primary buffer pointer hasset, and stores the read data into the buffer areas BF0 and BF1 of thebuffer RAM 122 by way of the disk data controller 120. Then themicro-controller 124 checks, at step 206, whether the sector from whichthe data has been read is a defective sector. If the sector is thedefective sector, the defective sector will be skipped at step 208. Atstep 210, the micro-controller 124 reads data beginning at the sector ofthe current track corresponding to the start address of the secondarybuffer pointer, and stores the read data beginning at the buffer areaBF3 of the start address that the secondary buffer pointer points.

The micro-controller 124 then checks, at step 212, whether the data iscompletely read or not. If the data is completely read, themicro-controller 124 searches the re-allocation sector that has replacedthe defective sector, i.e., the sector 2 at step 214, and reads there-allocation sector at step 216. Thereafter, at step 218, themicro-controller 124 stores the data read from the re-allocation sectorinto the buffer area BF2 that an address following the end address ofthe primary buffer pointer is pointing. Thereafter, the micro-controller124 transfers all the data stored in the buffer RAM 122 to the hostcomputer, at step 220.

Meanwhile, in case that the write data from the host computer is storedin the buffer RAM 122, the micro-controller 124 will perform anoperation opposite to the described data read operation. That is, thedata in the buffer area that the primary buffer pointer points to iswritten on the sectors of the corresponding track, and the data in thebuffer area that the secondary buffer pointer points to is written onthe sectors of the corresponding track. Of course, the defective sectoron the track is skipped while the primary buffer pointer goes over thesecondary buffer pointer. Thereafter, the data in the buffer area of anaddress following the end address that the primary buffer pointer pointsto is written on the re-allocation sector. The track seek is performedprior to writing the data on the re-allocation sector.

As described in the foregoing, the hard disk drive of the inventionreduces the number of searches during reading/writing (accessing) atrack having defectives, to improve a data transmission throughput of adrive so that the drive performance may be improved. In particular, thepresent invention may be effective for a hard disk drive which hasrelatively many defective sectors.

While there have been illustrated and described what are considered tobe preferred embodiments of the present invention, it will be understoodby those skilled in the art that various changes and modifications maybe made, and equivalents may be substituted for elements thereof withoutdeparting from the true scope of the present invention. In addition,many modifications may be made to adapt a particular situation to theteaching of the present invention without departing from the centralscope thereof Therefore, it is intended that the present invention notbe limited to the particular embodiment disclosed as the best modecontemplated for carrying out the present invention, but that thepresent invention includes all embodiments falling within the scope ofthe appended claims.

What is claimed is:
 1. A method for improving data access operation of ahard disk drive, comprising the steps of:determining whether a track ofa recording medium written on and read by said hard disk drive containsa defective sector; when the track of the recording medium contains saiddefective sector, re-allocating said defective sector with are-allocation sector from a re-allocation area of said recording medium;identifying as normal sectors any sector of the recording medium that isnot determined to be a defective sector; using a primary buffer pointerand a secondary buffer pointer within a memory of said hard disk driveto access all normal sectors of the recording medium, by using saidprimary buffer pointer to access all sectors of the recording mediumpreceding said defective sector and using said secondary buffer pointerto access all sectors of the recording medium following said defectivesector; and when the track containing said defective sector is beingaccessed during one of a read and a write operation, accessing allnormal sectors of said track except for said defective sector, and then,accessing said re-allocation sector and replacing said defective sector.2. The method of claim 1, wherein said primary buffer pointer has astart address and an end address of buffer areas in said buffer memory,said end address corresponding to the sector preceding said defectivesector.
 3. The method of claim 1, wherein said buffer memory has bufferareas for storing addresses of sectors of a current track of said harddisk drive.
 4. The method of claim 1, further comprising the stepsof:transferring data, during the read operation, from the normal sectorsand sequentially storing by address to a buffer memory while skipping anaddress of said buffer memory corresponding to said defective sector andthen transferring data from said re-allocation sector to the skippedaddress of said buffer memory; and sequentially transferring by addressduring the read operation all data stored in said bluffer memory to ahost computer.
 5. The method of claim 4, further comprising the stepsof:transferring data during the write operation, from the host computerto said buffer memory, said buffer memory storing data sequentially byaddress; writing the data stored in said buffer memory to thecorresponding normal sectors of a track while skipping the buffer memorycorresponding to said defective sector and then writing the buffermemory corresponding to said defective sector to said reallocationsector; and verifying that the writing of the data to said hard diskdrive is completed.
 6. A method for allocating defective sectors in adisk drive, comprising:using a buffer memory with buffer areas forstoring address data of sectors of a current track of a recordingmedium, and using primary and secondary buffer pointers to addresssectors of the current track of said recording medium; setting saidprimary buffer pointer with a starting address and an ending address ofbuffer areas in said buffer memory; setting said secondary bufferpointer with a starting address of a designated buffer area in saidbuffer memory corresponding to a sector following a defective sector ofthe current track; reading information data from the sector of thecurrent track set in accordance with the starting address and the endingaddress of said primary buffer pointer; determining whether the sectorsfrom which the information data is read contain a defective sector; whenthe sector from which the information data is read is a defectivesector, skipping said defective sector; reading information data fromthe sector of the current track set in accordance with the startingaddress of said secondary buffer pointer, and storing read databeginning at said designated area of said buffer memory; searching are-allocation sector that has replaced said defective sector; readinginformation data from the re-allocation sector, and storing read data ina buffer area that an address following the ending address of saidprimary buffer pointer is set; and transferring all information datastored in said buffer memory to a host computer.
 7. The method of claim6, further comprising the steps of:transferring information data fromsaid host computer to said buffer memory; writing the information datastored on said buffer memory to the sector of a track in accordance withthe starting address and the end address of said primary buffer pointer;when the end address of said primary buffer pointer is reached, the nextbuffer area corresponding to said defective sector is skipped; writingthe information data to the sector of a track in accordance with thestarting address of the secondary buffer pointer; verifying that thewriting of information to said recording medium is completed; searchinga re-allocation sector that has replaced said defective sector; andwriting the information data from a buffer area of said buffer memory tothe re-allocation sector, the buffer area of said buffer memorycorresponding to the address following the end address of said primarybuffer pointer.
 8. The method of claim 6, further comprising the step ofverifying the completion of the data read after reading information datafrom the sector of the current track set in accordance with the startingaddress of said secondary buffer pointer.
 9. A hard disk drive,comprising:a magnetic disk having a plurality of concentric tracks withsectors; a head accommodating reading and writing data transferred froma host computer from/to said magnetic disk; a buffer memory with bufferareas accommodating storing address data of sectors of a current trackof said magnetic disk, and primary and secondary buffer pointers toaddress sectors of the current track of said magnetic disk; and acontroller accommodating controlling data read and write operations andminimizing the number of searches of tracks containing defective sectorsduring said data read and write operations by:determining whether atrack of a recording medium contains a defective sector; when the trackof the recording medium contains said defective sector, re-allocatingsaid defective sector with a re-allocation sector from a re-allocationarea of said magnetic disk; and when the track containing said defectivesector is being accessed during one of said data read and writeoperation, controlling said primary and secondary buffer pointers toaccess all normal sectors of said track except for said defectivesector, and then, access said re-allocation sector which has replacedsaid defective sector to improve data transmission of said hard diskdrive.
 10. A method, comprising the steps of:setting a primary pointerwith a starting address and an end address of buffer areas in a memoryof a recording medium; setting a secondary pointer with a startingaddress of a designated buffer area in said memory corresponding to asector following a defective sector of a current track of said recordingmedium; transferring information data from a computer to said memory;writing the information data stored on said memory to a sector of atrack in accordance with the starting address and the end address ofsaid primary pointer; when the end address of said primary pointer isreached, the next buffer area corresponding to said defective sector isskipped; after skipping said defective sector, writing the informationdata to the sector of a track in accordance with the starting address ofthe secondary pointer; searching for a re-allocation sector that hasreplaced said defective sector; and writing the information data from abuffer area of said memory to said re-allocation sector, the buffer areaof said memory corresponding to the address following the end address ofsaid primary pointer.
 11. The method of claim 10, further comprising thestep of verifying that the writing of information data to said recordingmedium is completed after writing information data from the sector ofthe current track set in accordance with the starting address of saidsecondary pointer.
 12. The method of claim 11, wherein writing theinformation data stored on said memory to the sector of a track iscontrolled by a controller unit of said recording medium.